The present invention relates generally to power systems, and more particularly to power supply racks.
Mission critical systems, where even a temporary system shutdown is highly undesirable, play an increasingly important role in many essential industries. For example, mission critical systems are often used in the telecommunications industry, in hospitals, and in banking. To avoid system shutdowns, mission critical systems require highly reliable, redundant subsystems, such as redundant power supplies. In addition, many applications, such as telecommunication transmitters, require large amounts of power which may be provided by multiple power supplies.
The need for redundant power supplies capable of supplying large amounts of power has resulted in a corresponding increase in the use of hot-swap power supply technology. A hot-swappable power supply provides the ability to remove and replace the power supply from a power supply rack without turning off power to the rack. Thus, for example, in a power supply rack containing multiple or redundant removable power supply modules, should one module fail, the failed module can be replaced without interrupting the operation of other power supply modules. These racks of multiple power supplies may be used in high-power applications wherein the power supply outputs are ganged together. For example, the telecom industry has applications requiring up to 20,000 watts or more. This power may be provided by one or more racks, each containing multiple hot swappable power supplies ganged together.
However, the use of hot swappable power supplies poses many problems. For example, the removal of a power supply from a rack while power is still applied to the rack may result in arcing between the power supply connector pins and the corresponding rack connector sockets. Such arcing can severely injure an operator and may damage the power supply and the rack.
Furthermore, during a xe2x80x9chotxe2x80x9d insertion, the power supply input and output signals may be connected to the corresponding rack signals in an unsafe order. For example, power supply input power pins may contact corresponding rack power pins before the power supply ground pin comes in contact with a corresponding rack ground pin. This can result in a potentially dangerous xe2x80x9cfloatingxe2x80x9d condition, where the power supply is operational, but not grounded.
In addition, conventional hot-swappable power supply connectors are particularly susceptible to damage resulting from the frequent handling of the removable supplies. For example, power supply connectors are often damaged as a result of service personnel resting the supply on its connectors while placing the supply on the ground.
Furthermore, the sliding action itself during removal of the power supply from the rack often causes abrasion and gouges on the bottom of the power supply or damages to the rack. Conventional attempts to solve this problem typically utilize plastic guides, or the like, mounted in the rack to guide the power supply as it is being pulled in or out. However, these guides are relatively expensive, and often become damaged themselves during the removal or insertion process.
The present invention is generally related to a robust, safe, and sturdy power supply system, including a power supply rack used to receive power supplies. In one embodiment, the rack is configured to accept a hot swappable supply. That is, a power supply which can be removed from or inserted into the rack while power to the rack connectors is still on.
In one embodiment, the rack is configured to receive a power supply which has an overall rectangular shape. In order to ensure that the power supply is properly oriented while being inserted into a rack, a keying system is provided on a first side, such as the rear of the power supply housing. In one embodiment, the keying is provided by one or more pins, posts, or the like, projecting from a connector-side of the power supply. For example, one or more key pins, which can also act as guide pins or posts, may extend rearward from one or more rear connectors. In one embodiment, these key pins or posts fit into corresponding receptacles on the rack side connectors. Thus, if the user attempts to insert the power supply upside down or sideways, the key pins will strike into a portion of the rack chassis before the power supply connectors and corresponding rack connectors can come into direct contact. Furthermore, in one embodiment, the keys are located so that if the power supply is inserted in an incorrect orientation, the keys will not strike the rack connectors. Thus, connector damage resulting from the improper insertion of the power supply into the rack is greatly reduced.
In addition, in one embodiment, standoff posts or the like are provided extending rearward from the supply. The standoffs advantageously extend past the connector pins or other sets of signal, power or key pins, so that if the power supply is rested on the ground, connector-side down, the power supply will rest on the standoffs, rather than the connector pins. Thus, the standoffs protect the connectors and connector pins from the type of damage that often results when a conventional power supply is rested on its connectors. The rack is optionally provided with openings to accommodate the standoffs upon insertion of the power supply into the rack.
In one embodiment, the rack has connectors which mate with connectors on the rear of the power supply. The power supply connectors include an AC input connector, a DC output connector, and a control signal connector. In one embodiment, the rack is configured to provide single-phase AC power to the power supply AC input connector. In another embodiment, the rack is configured to provide three-phase AC power to the power supply AC input connector. In one embodiment, at least two power supply AC connector pins have relatively staggered lengths, thereby ensuring the safety of the system when the power supply is removed or inserted into the rack.
Thus, for example, in the case of a power supply which has a connector configured to receive single phase AC power, a common pin, a first polarity line pin, a second polarity line pin, and a precharge pin are provided. In one embodiment, the common pin extends the furthest out, thereby ensuring that when the power supply is inserted into the rack, the first connection made will couple the power supply common pin to a rack common point. In another embodiment, a first polarity pin and a precharge pin are shorter in length than the common pin. Thus, when the power supply is inserted into the rack, after the common connection is made, the first polarity line pin and the precharge pin will be connected to corresponding rack connections. This staggered arrangement ensures that a power supply internal EMI filter is charged before the second polarity line is connected. Thus, inrush current, which could cause arcing and pin damage, is thereby reduced. In addition, the second polarity pin is advantageously shorter than the first polarity pin. Thus, the complete AC connection will only be made after the common, the first polarity, and the precharge connections are made. In one embodiment, the control signal connector may have pins similarly staggered to ensure the safe turn-on and turn-off of the power supply. The rack has corresponding connectors which mate with the power supply connectors and which accommodate the different pin lengths.
In another embodiment, a latch is provided to latch the power supply into a rack station. In one embodiment, the latch includes a finger portion which rotatably extends from the power supply into a receiving slot on the rack. In one embodiment, the rack includes a structure configured to kick the finger portion out of the way if the finger portion is inadvertently extended while the supply is being inserted into a rack. Thus, damage to the latch is prevented.
In one embodiment, the rack is configured to receive a power supply whose height and width are substantially the same. In one embodiment, the rack is a standard 19xe2x80x3 width rack which can accommodate up to three 5xe2x80x3xc3x975xe2x80x3 power supply modules. In another embodiment, the power supply rack is a 23xe2x80x3 rack and can receive four 5xe2x80x3xc3x975xe2x80x3 power supply modules.
In addition, one side of the power supply housing, such as the bottom side, may include one or more mounting assemblies, such as threaded nuts used to receive fasteners, such as screws. Thus, the power supply may be more permanently mounted into the rack if so desired.